Magnetic tape cartridge having triple lid assembly

ABSTRACT

A magnetic tape cartridge includes a casing having a tape chamber defined therein for accommodating a reeled magnetic recording tape and, also, box arms protruding outwardly from a front wall section of the casing so as to leave a loading bay that opens upwardly, frontwardly and downwardly and is thus delimited by upwardly, frontwardly and downwardly oriented open areas. The casing includes a lid assembly for selectively concealing and exposing that portion of magnetic recording tape and including front, top and rear lids operatively linked together. The front and top lids are adapted to selectively open and close the frontwardly and upwardly oriented open areas of the loading bay, respectively, while the rear lid is positioned within the loading bay and adapted to selectively open and close a space delimited between the front and the rear lid. At least first and second, generally cylindrical bosses extend between the top and bottom panels of the casing and are positioned at respective points of intersection between inner side walls of the box arms, which confront the loading bay, and the front wall section so as to partially protrude laterally into the loading bay. Each boss has a positioning hole defined axially therein so as to extend exteriorly through one of the top and bottom walls of the casing and is comprised of upper and lower boss segments aligned axially with each other. The upper boss segment has an outer diameter smaller than that of the lower boss segment.

This application is a divisional of application Ser. No. 08/677,779,U.S. Pat. No. 5,687,047 filed on Jul. 10, 1996, which is a continuationof application Ser. No. 08/350,075, filed on Nov. 29, 1994, nowabandoned, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a magnetic tape cartridge ofa type having a protective lid assembly and, more particularly, to amechanism in the magnetic tape cartridge for selectively opening andclosing the protective lid assembly for exposing and concealing portionof a length of magnetic recording tape in relation to an in formationrecording and/or reproducing head assembly.

2. Description of the Prior Art

The magnetic tape cartridge of the type referred to above includes, forexample, an 8-mm video tape cartridge of a structure shown in FIG. 11.This illustrated magnetic tape cartridge comprises a casing 1 includesgenerally rectangular flat top and bottom panels, opposite side wallsand front and rear walls, all of said side, front and rear walls beingdisposed between the top and bottom panels to keep them spaced apart adistance to define a tape chamber. The front wall is set back inwardlyto define a generally U-shaped loading bay 6 in the casing 1 whileleaving box arms on respective sides thereof that protrudes forwardly ina direction perpendicular to the longitudinal sense of the magnetic tapecartridge. Specifically, the loading bay 6 is delimited by inner sidewalls 7 of the respective box arms, that confront with each other, andthe inwardly set-back front wall 8. This casing 1 accommodates therein apair of reels to which opposite ends of a length of magnetic recordingtape are anchored, respectively. A portion of the length of magneticrecording tape 2 drawn from one of the reels 3 and emerging outwardlyfrom one of the box arms is adapted to travel towards the other of thebox arms across the loading bay 6 and is then turned around the other ofthe reels.

The loading bay 6 is known as a space defined to permit various tapeloading and unloading elements, forming parts of a tape loading andunloading mechanism in a magnetic recording and/or reproducing devicewith which the magnetic tape cartridge works, to be selectively insertedthereinto or withdrawn therefrom in response to loading or unloading ofthe tape magnetic tape cartridge. Specifically, when the magnetic tapecartridge is loaded in the magnetic tape player, that portion of themagnetic recording tape 2 traversing the loading bay 6 between the boxarms is drawn out of the loading bay 6 and turned generally halfwayaround the rotary head-carrier cylinder in the tape player, but when themagnetic tape cartridge is to be removed from the tape player, thatportion of the magnetic recording tape 2 is withdrawn into the loadingbay 6.

While the magnetic tape cartridge is not in use, e.g., while themagnetic tape cartridge is not inserted into the magnetic tape player,that portion of the magnetic recording tape extending between the boxarms across the loading bay 6 is protected by a transversely extendinglid assembly which is generally comprised of front and rear lids 17 and20 facing front and rear surfaces of the length of magnetic recordingtape, respectively, the front and rear lids 17 and 20 are operativelylinked together to move between open and closed positions as indicatedby the phantom and solid lines in FIG. 11, respectively.

The inner side walls 7 of the respective box arms have respective guidegrooves 40 defined therein in a mirror image fashion with each other forguiding the front and rear lids 17 and 20 in unison between the open andclosed positions as is well known to those skilled in the art. Thus,movement of the double lid assembly from the closed position towards theopen position allows that portion of the magnetic recording tape 2 to beexposed to the outside of the magnetic tape cartridge while movement ofthe double lid assembly from the open position towards the closedposition allows that portion of the magnetic recording tape 2 to beconcealed in a space between the front and rear lid 17 and 20 as shown.

In order for the magnetic tape cartridge to be accurately positionedrelative to the head-carrier cylinder when it is loaded in the tapeplayer, the casing 1 has a pair of positioning holes 9 each extendinginto a respective boss 11 through the bottom panel. Each boss 11 issubstantially cylindrical in section and extends between the top andbottom panels of the casing 1 and is located generally at a junctionbetween the front wall 8 and the associated side wall 7 of the box armwith a lateral portion 11a of the outer periphery of the boss 11protruding into the loading bay 6. Protrusion of the lateral portion 11a of the outer periphery of each of the cylindrical bosses 11 into theloading bay 6 is necessitated to secure, within a limited space insidethe casing 1, a sufficient outer diameter of each boss 11 which is inturn necessitated to secure a required diameter of the respectivepositioning hole 9.

On the other hand, as part of the attempt to render the magneticrecording and/or reproducing system to be compact, attempts have beenmade to make the 8-mm video tape cartridge compact. To this end, it hasbeen suggested, as disclosed in, for example, the Japanese Laid-openPatent Publication No 57, 210489, to use a triple lid assemblyincluding, in addition to the front and rear lids, a top lid operativelylinked with the front and rear lids to open an upper region above thatportion of the magnetic recording tape 2 in response to movement of thefront and rear lids towards the open position. The use of the top lid incombination with the front and rear lids makes it possible to increasethe opening of the lid assembly while preserving a limited area of theloading bay.

A problem of interest would arise when attempt is made to employmechanisms of the 8-mm video tape cartridge, in which the outer lateralportions of the cylindrical bosses necessarily protrude into the loadingbay, in the magnetic tape cartridge of a type employing the triple lidassembly referred to above. In the magnetic tape cartridge designed toassist the system to be rendered compact, the area of the side wall 7 ofeach box arm is reduced and, therefore, protrusion of the outer lateralportions 11a of the respective cylindrical bosses 11 into the loadingbay 6 often constitutes a cause of interference between left and rightends of the rear lid 20 and those outer lateral portions 11a of therespective bosses 11.

In order to substantially eliminate this problem, it may be envisaged toeither reduce the width of the rear lid 20 as measured in a directionfrom one side wall to the other side wall of the casing, or relocate theguide grooves 40 for the rear lid 20 to a position further away from thefront wall 8. It has, however, been found that reduction in width of therear lid 20 may result in formation of a gap between each side wall 7and the adjacent end of the rear lid 20 through which dust may depositon that portion of the magnetic recording tape, whereas relocation ofthe guide grooves 40 requires an increase of the area of each side wall7 facing the loading bay 6 and does therefore bring about a resultcontrary to the attempt to make the system compact.

SUMMARY OF THE INVENTION

The present invention has accordingly been devised to provide animproved magnetic tape cartridge of a type employing a triple lidassembly, wherein improvement is made to the design and the shape ofeach of the cylindrical bosses having the positioning hole definedtherein, thereby to make it possible to render the system to be compactand also to ensure a smooth movement of the lid assembly withoutinterfering with the casing.

To this end, the present invention provides a magnetic tape cartridgeincluding a casing having top and bottom panels and a peripheral walldisposed between the top and bottom panels to keep them spaced apart adistance to define a tape chamber. The peripheral wall includes frontand rear wall sections and a pair of side wall sections, all assembledtogether to render the tape cartridge to represent a generallyrectangular box-like configuration and, also, box arms protrudingoutwardly from the front wall section in communication with the tapechamber so as to leave a loading bay that opens upwardly, frontwardlyand downwardly and is thus delimited by upwardly, frontwardly anddownwardly oriented open areas. A pair of freely rotatable reels areaccommodated within the casing, and a length of magnetic recording tapehas its opposite end anchored to the respective reels and adapted totravel from one reel to the other reel, when the tape cartridge is inuse within a magnetic recording and/or reproducing apparatus, with aportion of the length of magnetic recording tape traversing across theloading bay at a location spaced a distance from the front wall section.

The magnetic tape cartridge of the present invention also includes a lidassembly for selectively concealing and exposing that portion ofmagnetic recording tape and including front, top and rear lidsoperatively linked together. The front lid is carried by the casing forpivotal movement about a transverse axis, extending parallel to thefront wall section, between first and second positions. This front lidwhen in said first position opens the frontwardly oriented open area ofthe loading bay, but when in said second closes the frontwardly orientedopen area of the loading bay. On the other hand, the top lid is hingedlyconnected with the front lid and movable between third and fourthpositions in unison with the movement of the front lid between the firstand second positions, respectively. This top lid when in said thirdposition closes the upwardly oriented open area of the loading bay, butwhen in said fourth position, opens the upwardly oriented open area ofthe loading bay. Again, the rear lid is hingedly connected to the toplid and movable between fifth and sixth positions in unison with themovement of the top lid between the third and fourth positions,respectively. This rear lid when in said fifth position is positionedwithin the loading bay and rearwardly of the front lid to substantiallyconfine that portion of magnetic recording tape within a space delimitedbetween the front lid in the first position and the rear lid in thefifth position, but when in said sixth position, positioned generallyabove the loading bay and in part beneath the front lid in the secondposition and in part beneath the top lid in the rear position. Thatportion of magnetic recording tape is exposed to the outside when thefront lid is moved to the second position accompanied by movement of thetop lid to the third position which is in turn accompanied by movementof the rear lid to the sixth position.

At least two cylindrical bosses extend between the top and bottom panelsof the casing within the casing and each boss is positioned at a pointof intersection between an inner side wall of the respective box arm,which confronts the loading bay, and the front wall section so as topartially protrude laterally into the loading bay. Each boss has apositioning hole defined axially therein so as to extend exteriorlythrough one of the top and bottom walls of the casing and is composed ofupper and lower boss segments aligned axially with each other. The upperboss segment has an outer diameter smaller than that of the lower bosssegment.

According to the present invention, each of the cylindrical bosses iscomprised of the top and bottom boss segments integral with therespective top and bottom casing halves, said top boss segment having anouter diameter smaller than that of the bottom boss segment to allowthat lateral portion of the periphery of the top boss segment toprotrude into the loading bay a radial distance smaller than thatlateral portion of the periphery of the bottom boss segment.Accordingly, it is possible to avoid any possible interference betweenthe bosses and the rear lid while a sufficient diameter is secured ineach of the positioning holes and, therefore, a smooth movement of therear lid between the lowered and lifted position is possible, therebymaking it possible to make the system compact.

Preferably, a transit between the top and bottom boss segments in eachboss is defined by the outwardly tapering surface formed at the upperend of the bottom boss segment. Accordingly, even though the path ofmovement of the rear lid between the lowered and lifted positions isdefined at a position slightly rearwardly with respect to the ideal pathof movement thereof, the rear lid may slide over the outwardly taperingsurface to facilitate a smooth movement of the rear lid.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other objects and features of the present invention will becomeclear from the following description taken in conjunction with preferredembodiments thereof with reference to the accompanying drawings, inwhich like parts are designated by like reference numerals and in which:

FIG. 1 is a perspective view of a magnetic tape cartridge embodying thepresent invention;

FIG. 2 is a bottom plan view of the magnetic tape cartridge;

FIG. 3 is a fragmentary side sectional view, on an enlarged scale, of afront portion of the magnetic tape cartridge taken along the line A--Ashown in FIG. 1;

FIG. 4 is an exploded view, on an enlarged scale, of that front portionof the magnetic tape cartridge;

FIG. 5 is an exploded view, on a further enlarged scale, showing one ofbosses employed in the magnetic tape cartridge embodying the presentinvention;

FIG. 6 is an exploded view, on a further enlarged scale, showing alinkage between top and rear lids employed in the magnetic tapecartridge embodying the present invention;

FIG. 7 is a side sectional view, on a further enlarged scale, showing amodified linkage between the top and rear lids;

FIG. 8A is a view similar to FIG. 3, showing a different embodiment ofthe present invention;

FIG. 8B is a fragmentary side sectional view, on a further enlargedscale, showing a portion encompassed in an oval in FIG. 8A;

FIG. 9 is a fragmentary side sectional view, on a further enlargedscale, showing a modified guide groove employed in the magnetic tapecartridge of the present invention;

FIGS. 10A to 10C are schematic diagrams showing further modified formsof the guide grooves employed in the magnetic tape cartridge of thepresent invention, respectively; and

FIG. 11 is a fragmentary side sectional view of a front portion of theconventional magnetic tape cartridge.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring now to FIGS. 1 to 7, a magnetic tape cartridge shown thereinaccording to a first preferred embodiment of the present inventioncomprises, as best shown in FIGS. 1, 2 and 4, a casing 1 includinggenerally rectangular flat top and bottom panels, opposite side walls 24and front and rear walls (only the front wall being indicated by 8), allof said side, front and rear walls being disposed between the top andbottom panels to keep them spaced apart a distance to define a tapechamber. In practice, however, the casing 1 is generally made ofplastics and includes top and bottom casing halves 1a and 1b joinedtogether to render the casing 1 to represent a generally rectangular,generally flattened box-like configuration as is well known to thoseskilled in the art.

The casing 1 accommodates therein a pair of reels 3 rotatably housed inposition within the tape chamber of the magnetic tape cartridge. Thesereels 3 have opposite ends of a length of magnetic recording tape 2anchored thereto, respectively, so that a length of magnetic recordingtape 2 drawn from one of the reels 3 can be taken up around the other ofthe reels 3 during the use of the magnetic tape cartridge in a magnetictape player.

In order for that portion 2a of the length of magnetic recording tape 2,which extends outside the casing 1 along the front wall 8 thereof, to beoperatively brought into engagement with the rotary head-carriercylinder in a magnetic tape player (not shown), the casing 1 hasleft-hand and right-hand box arms 4 protruding frontwardly therefrom soas to terminate at a position spaced a distance away from the front wall8 of the casing 1, said box arms 4 opening outwardly in a direction awayfrom the front wall 8 of the casing 1. The box arms 4 has respectiveinner side walls 7 which cooperate with the front wall 8 of the casing 1to define a loading bay 6. As discussed previously, the loading bay 6opens upwardly, downwardly and frontwardly and is known as a spacedefined to permit the various tape loading and unloading elements to beselectively inserted thereinto or withdrawn therefrom in response toloading or unloading of the tape magnetic tape cartridge into or fromthe magnetic tape player.

Thus, it will readily be seen that the length of magnetic recording tape2 that is to travel one of the reels 3 towards the other of the reels 3across the loading bay 6 extends through one of the box arms 4 adjacentsuch one of the reels 3 so as to emerge outwardly from the casing 1 andthen extend into the other of the box arms 4 adjacent such other of thereels 3, with that portion 2a of the magnetic recording tape 2 havingtraversed the loading bay 6 in a direction spaced from and generallyparallel to the front wall 8 of the casing 1. In order for that portion2a of magnetic recording tape 2 to be smoothly guided across the loadingbay 6, front upright edges of the inner side walls 7 defining parts ofthe respective box arms 4 are chamfered as shown by 5 in FIG. 5 todefine a chamfered guide. Alternatively, a rotatably supported spindleor roller may be employed for the chamfered guide.

As best shown in FIG. 3, the casing 1 has front and rear pairs ofpositioning holes 9 and 10 defined in the bottom panel thereof.Specifically, each of the positioning holes 9 of the front pair extendscompletely across the thickness of the bottom panel of the casing 1 andthen into a respective cylindrical boss 11 formed at the junctionbetween the adjacent inner side wall 7 and the front wall 8. Consideringthe casing 1 made up of the top and bottom casing halves 1a and 1b, eachcylindrical boss 7 is also made up of top and bottom boss segments 12and 13 which are formed integrally with the top and bottom panels of thecasing 1 and which are concentrically abutted together, when the top andbottom casing halves 1a and 1b are joined together, to complete therespective cylindrical boss 11.

As discussed previously, each of the cylindrical bosses 11 must have asufficient outer diameter in order to secure a required diameter of eachof the positioning holes 9 within a limited space available inside thecasing 1 so that the tape cartridge can be made compact in size. Forthis reason, as clearly shown in FIG. 5, it has been a customarypractice to allow that lateral portion 11a of the outer periphery ofeach cylindrical boss 11 protrudes into the loading bay 6 as shown inFIG. 11. However, in the practice of the present invention, only thebottom boss segment 13 of each cylindrical boss 11 integral with thebottom casing half 1b has the associated positioning hole 9 definedtherein and also has an outer diameter sufficient to secure the requireddiameter of the associated positioning hole 9 whereas the top bosssegment 12 integral with the top casing half 1a has an outer diameter assmall as possible, i.e., a reduced outer diameter as compared with thatof the bottom boss segment 13. By so doing, it will readily be seenthat, even though a lateral portion 13a of the outer periphery of thebottom boss segment 13 protrudes into the loading bay 6 a radialdistance corresponding to that over which that portion 11a of the outerperiphery of each boss 11 shown in FIG. 11 protrudes, a lateral portion12a of the outer periphery of the top boss segment 12 is radiallyinwardly set back relative to that lateral portion 13a of the outerperiphery of the bottom boss segment 13 to thereby provide a sufficientspace for accommodating a movement of an associated one of opposite endsof a rear lid 20 as will be described later.

In other words, while each cylindrical boss 11 shown in FIG. 11 has anouter diameter uniform over the entire length thereof between the topand bottom panels of the casing 1, each cylindrical boss 11 employed inthe practice of the present invention has large and reduced diameterswhich are occupied by the bottom and top boss segments 13 and 12,respectively, with an upper end of said bottom boss segment 13 chamferedat 15 so as to taper radially inwardly towards the associated top bosssegment 12 as best shown in FIG. 3. Thus, when the top and bottom casinghalves 1a and 1b are joined together to complete the magnetic tapecartridge, lower ends of the top boss segments 12 are received withinrespective bearing holes or recesses 14 defined in the upper ends of theassociated bottom boss segments 13 in coaxial relation with thecorresponding positioning holes 9.

After the top and bottom casing halves 1a and 1b have been joinedtogether with the lower ends of the top boss segments 12 engaged in thebearing holes 14 in the upper ends of the bottom boss segments 13,tapping screws 16 are inserted into the positioning holes 9 in thebottom boss segments 13 and are then threadingly tapped into the topboss segments 12 to connect the top and bottom casing halves 1a and 1btogether. So far illustrated, these tapping screws 1 6 are utilized toserve as two of a plurality of fastening members used to firmly connectthe top and bottom casing halves 1a and 1b together. However, the use ofthe tapping screws 16 is not essential in the practice of the presentinvention if the other fastening members serve the purpose of connectingthe top and bottom casing halves 1a and 1b together.

Where each of the cylindrical bosses 11 is concurrently used as aconnecting boss such as shown, the corresponding tapping screw 16 istapped into the associated positioning hole 9 with its head 16apositioned deep into the positioning hole 9 to secure the associatedpositioning hole 9 beneath the head 16aof the respective tapping screw16 as shown by the phantom line in FIG. 3.

That portion 2a of the length of magnetic recording tape 2 extendingbetween the chamfered guides 5 of the box arms 4 across the loading bay6 is, when the magnetic tape cartridge is not in use, concealed and,therefore, protected by a triple lid assembly including a front lid 17,a top lid 19 and a rear lid 20 all made of plastics and extendingsubstantially parallel to each other between the box arms 4. The detailsof the triple lid assembly will now be described.

As best shown in FIGS. 1, 3 and 4, the front lid 17 is of one-piececonstruction including a generally rectangular plate 21 adapted to closea front opening of the loading bay 6 and, also, forwardly orientedopenings of the box arms 4, and left-hand and right-hand arms 22protruding from opposite ends of the rectangular plate 21 in a directionperpendicular thereto and towards the rear of the casing 1. Theleft-hand and right-hand arms 22 have respective axially aligned pivotpins 23 protruding therefrom in a direction close towards each other androtatably engaged in respective bearing holes 25 defined in the sidewalls 24 of the casing 1. Thus, it will readily be seen that the frontlid 17 is pivotable about a common axis of the pivot pins 23 between aforwardly oriented position, in which as best shown by the solid line inFIGS. 1 and 3, the rectangular plate 21 lies parallel to that portion 2aof magnetic recording tape 2 while closing the front opening of theloading bay 6 and the forwardly oriented openings of the box arms 4, andan upwardly oriented position as shown by the phantom line in FIG. 3.However, by the action of a spring element such as a torsion spring 26mounted on at least one of the pivot pins 23 with its opposite endsconnected respectively to the front lid 17 and the associated side wall24 of the casing 1, the front lid 17 is normally biased to assume theforwardly oriented position as shown by the solid line in FIGS. 1 and 3.

The top lid 19 is also of one-piece construction including a generallyrectangular plate 27 and left-hand and right-hand end walls 28protruding opposite ends of the rectangular pate 21 in a directionperpendicular thereto and downwardly as viewed in FIG. 4. The left-handand right-hand end walls 28 have respectively axially aligned guide pins29 protruding therefrom in a direction close towards each other. Thistop lid 19 is supported for movement between a front position, in whichas shown by the solid line in FIGS. 1 and 3, the top lid 19 closes theupwardly oriented opening of the loading bay 6 including a spaceimmediately above that portion 2a of magnetic recording tape 2, and arear position substantially above the top panel of the casing 1 as shownby the phantom line in FIG. 3. This movement of the top lid 1 9 betweenthe front and rear positions takes place in response to the movement ofthe front lid 17 between the forwardly and upwardly oriented positionsand, for this purpose, the front and top lids 1 7 and the 19 areoperatively linked together in a manner which will now be described.

As best shown in FIGS. 3 and 4, the end walls 28 integral with theopposite ends of the rectangular plate 27 of the top lid 19 protrude adistance outwardly from a front edge 27a of the rectangular plate 27 todefine respective bearing arms 31. These bearing arms 31 are formed withaxially aligned pivot pins 30 which are pivotally engaged in bearingpieces 32 integral with an upper edge 21a of the rectangular plate 21 ofthe front lid 17, which bearing pieces 32 are so positioned as to beencompassed within the distance between the opposite end walls 28 of thetop lid 19.

Also, for the purpose as will subsequently become clear, the top lid 19has a rib 35 integrally formed with an inner surface of the rectangularplate 27 and having its opposite ends formed with axially inwardlyextending bearing holes 35a. Although the rib 35 is shown to extend asubstantial distance longitudinally of the rectangular plate 27 and maytherefore be utilized to reinforce the top lid 19, two separate bearingprotuberances having the respective bearing holes 35a defined thereinmay be employed in place of the single rib 35.

Thus, it will be understood that the front lid 17 and the top lid 19 arepivotally connected with each other, one pivotable relative to the otherabout a common axis extending between the pivot pins 30. The guide pins29 integral with the respective end walls 28 are slidably engaged inrespective guide grooves 33 defined in outer surfaces of the side walls24, said guide grooves 33 being so shaped and so curved that, as the toplid 19 is moved from the front position, shown by the solid line in FIG.3, towards the rear position shown by the phantom line, the top lid 1 9substantially in flush with the top panel of the casing 1 is upwardlyshifted while moving rearwardly of the casing 1 and finally assumes aposition generally above the top panel of the casing 1 upon arrival atthe rear position. As a matter of design, this movement of the top lid19 from the front position towards the rear position follows themovement of the front lid 1 7 from the forwardly oriented positiontowards the upwardly oriented position.

As best shown in FIGS. 3, the rear lid 20 is also operatively linkedwith the front lid 17 through the top lid 19 in a manner as will bedescribed subsequently and is movable between a lowered position, inwhich as shown by the solid line the rear lid 20 is positionedrearwardly of that portion 2a of magnetic recording tape 2, and a liftedposition in which as shown by the phantom line the rear lid 20 assumes aposition generally above the loading bay 6 to thereby clear the rear ofthat portion 2a of magnetic recording tape 2 for permitting the tapeloading and unloading elements to engage that portion 2a of magneticrecording tape 2. Specifically, this rear lid 20 is moved from thelowered position towards the lifted position as the top lid 19 is movedfrom the front position towards the rear position, and vice versa.

For this purpose, as shown in FIGS. 3 and 4, the rear lid 20 includes anupper edge 20a having its opposite ends formed with respective bearingprotuberances 34 which are in turn formed with axially aligned bearingpins 36 extending therefrom so as to confront with each other. The rearlid 20 is pivotally coupled with the top lid 19 with the bearing pins 36pivotally engaged in the respective bearing holes 35a in the rib 35integral with the top lid 19.

The rear lid 20 also includes legs 37 formed integrally therewith so asto protrude rearwardly therefrom adjacent a lower edge opposite to theupper edge 20a, which legs 37 are formed integrally with respectiveguide pins 39 that: protrude outwardly in a direction away from eachother. These guide pins 39 are slidingly engaged in generally J-shapedguide grooves 40, respectively, each of said guide grooves 40 beingdefined in the inner side wall 7 of the associated box arm 4 at alocation frontwardly of that portion 13a of the outer periphery of therespective cylindrical boss 13. Thus, it will readily be understoodthat, as the top lid 19 is moved from the front position towards therear position with the guide pins 29 slidingly guided along therespective guide grooves 33, the rear lid 20 is moved from the loweredposition towards the lifted position with the guide pins 39 slidinglyguided along the respective guide grooves 40 and that, at the time thetop lid 19 is held at the rear position with the front lid 17 in theupwardly oriented position held substantially in flush with the top lid1 9 as shown by the respective phantom lines in FIG. 3, the rear lid 20is held immediately below the pivotal joint between the front and toplids 17 and 1 9 and generally above the loading bay 6 as shown by thephantom line in FIG. 3.

The triple lid assembly of the construction described above operates; inthe following manner.

When the magnetic tape cartridge embodying the present invention isloaded into the magnetic tape player (not shown) in the known manner,the front lid 17 is pivoted about the common axis of the pivot pins 23against the biasing force of the torsion spring 26 so as to move fromthe frontwardly oriented position towards the upwardly orientedposition. As the front lid 17 so moves, it pushes the top lid 19 to movethe latter from the front position towards the rear position with theguide pins 29 slidingly guided along the guide grooves 33. During themovement of the top lid 19 towards the rear position, the front edge 27aof the rectangular plate 27 of the top lid 19 is shifted upwardly of theloading bay 6 and is then moved rearwardly of the casing 1 because ofthe curved, profile of the guide grooves 33 and finally assumes the rearposition, shown by the phantom line in FIG. 3, substantiallysimultaneously with arrival of the front lid 17 at the upwardly orientedposition as shown by the phantom line in FIG. 3.

Simultaneously with the start of movement of the top lid 19 from thefront position towards the rear position having been pushed by the frontlid 1 7, the rear lid 20 starts its movement from the lowered positiontowards the lifted position with the guide pins 39 slidingly guidedalong the guide grooves 40 so as to move upwardly in the respectiveguide grooves 40. Thus, the rear lid 20 is first moved a slight distancerearwardly and is then moved upwardly and rearwardly and finally assumesthe lifted position at which the rear lid 20 occupies a position belowthe front and top lids 17 and 19, then in flush with each other, andabove the loading bay 6, allowing that portion 2a of magnetic recordingtape 2 to be completely exposed to the outside in readiness forengagement with the loading and unloading elements in the tape player.

It is to be noted that, during the movement of the rear lid 20 from thelowered position towards the lifted position, the opposite ends of thetop lid 20 move adjacent the lateral portions 12a of the outerperipheries of the respective top boss segments 12. However, since asone of the features of the present invention the lateral portion 12a ofthe outer periphery of each top boss segment 12 is radially inwardly setback relative to the lateral portion 13a of the outer periphery of themating bottom boss segment 13, it is possible to allow the opposite endsof the rear lid 20 to move closer to the cylindrical bosses 11 than thatwhere each cylindrical boss has a uniform outer diameter over the entirelength thereof such as shown in and discussed with reference to FIG. 11and, hence, an upper region of, each of the guide grooves 40 canadvantageously be defined at a location close towards the lateralportion 12a of the outer periphery of each top boss segment 12 with nopossibility of the cylindrical bosses 11 interfering the movement of therear lid 20.

Also, the upper end of each of the bottom boss segments 13 has beendescribed and shown as chamfered so as to taper radially inwardlytowards the associated top boss segment 12 to thereby define theoutwardly tapering surface 15. Accordingly, where a clearance isprovided in the pivotal joint between the front lid 17 and the top lid19 and between the top lid and the rear lid 20 and, also, between eachguide pin 39 and the associated guide groove 40 to secure a smoothopening or closure of the triple lid assembly and the path of movementof the rear lid 20 may therefore be displaced a slight distancerearwardly from an ideal path of movement thereof, the rear lid 20 maybe allowed to ride over the outwardly tapering surfaces 15 in the bosses11.

As best shown in 3, 4 and 6, a portion of the upper edge 20a of the rearlid 20 between the 36 bearing pins 36 is integrally formed with agenerally elongated wall member 50 that extends over that portion of theupper edge 20a for slidingly bearing the rib 35 from below. So far shownin FIGS. 3 and 4, the elongated wall member 50 protrudes generallyforwardly in a direction conforming to the direction of thickness of therear lid 20, but it may protrude forwardly and rearwardly with respectto the directions of thickness of the rear lid 20 as shown in FIG. 7. Ineither case, the amount of forward protrusion of the elongated wallmember 50 must be so chosen that a free face of the elongated wallmember 50 remote from the rear lid 20 will not interfere the movement ofthe top lid 19 and may be brought into contact therewith only when therear lid 20 is completely moved to the lifted position shown by thephantom line in FIG. 3.

So long as the top and rear lids 19 and 20 are held at the front andlowered positions, respectively, a gap between the inner surface of thetop lid 19 and the upper edge 20a of the rear lid 20 is closed by therib 35 formed integrally with the top lid 19 so as to protrudedownwardly therefrom. Also, although a slight gap may be formed betweena lower peripheral surface portion of the rib 35 and the elongated wallmember 50, a passage communicating between spaces on respective sides ofthe rear lid 20 through such slight gap represents a curved detour sincethe elongated wall member 50 substantially encircles the lowerperipheral surface portion of the rib 35, thereby minimizing thepossibility that dust entering inwardly through a gap between the toplid 19 and the top panel of the casing 1 will reach a portion of theloading bay 6 where that portion 2a of magnetic recording tape 2 issituated.

Although not always essential in the practice of the present invention,the front lid 17 may have an elongated groove 60 defined in an innersurface of the rectangular plate 21 adjacent a lower edge so as toextend lengthwise thereof, as best shown in FIG. 3, so that, when and solong as the front lid 17 and the rear lid 20 are in the forwardlyoriented and lowered positions, respectively, a lower edge of the rearlid 20 is received in the elongated groove 60 to thereby close thatportion of the loading bay 6, where that portion 2a of magneticrecording tape 2 is situated, for avoiding any possible ingress offoreign matter into that portion of the loading bay 6.

It is to be noted that, although in the foregoing embodiment only thetop boss segments 12 have been shown and described as having the reducedouter diameter as compared with the outer diameter of the bottom bosssegments 13, the bottom boss segments 13 may have an equally reducedouter diameter depending upon the profile of the path of movement of therear lid 20 between the lowered and lifted positions.

FIGS. 8A and 8B illustrate the magnetic tape cartridge according to asecond preferred embodiment of the present invention which issubstantially similar to that according to the foregoing embodiment, butdiffers therefrom in respect of the details of each of the guide grooves40 that are formed on the inner side walls 7 of the respective box arms4. In describing the second preferred embodiment of the presentinvention, reference will be made only to one of the guide grooves 40since the latter are formed in the respective inner side walls 7 in amirror image fashion relative to each other.

As shown in FIGS. 8A and 8B, the guide groove 40 is delimited by innerside surfaces 40a and 40b spaced from each other a distance sufficientto accommodate the diameter of the associated guide pin 39. This guidegroove 40 has an upper end opening upwardly at an upper face 70 of theassociated inner side wall 7. However, in order for the rear lid 20 tobe lifted an increased distance upwardly when held in the liftedposition as shown by the phantom line, a generally triangularprotuberance 71 is fixedly mounted on, or formed integrally with, theupper face 70 of the inner side wall 7 and protrude therefrom so as toconverge upwardly as best shown in FIG. 8B. The triangular protuberance71 has a rear inclined face 71a continued to the inner side surface 40ato render an upper end of the guide groove 40 to represent asubstantially upwardly flared configuration in cooperation with an upperend of the inner side surface 40b which is inclined at 73 to separateaway from the inner side surface 40a.

The use of the triangular protuberance 71 protruding upwardly from theupper face 70 of the inner side wall 7 such as described above mayresult in an interference between it and the inner surface of therectangular plate 27 of the top lid 19 when the top lid 19 is moved fromthe rear position shown by the phantom line to the front position shownby the solid line. In order to avoid this interference, a recess 72 isdefined in an inner surface of the rectangular plate 27 of the top lid19 to accommodate the triangular protuberance 71 when the top lid 19 isin the front position.

According to the second preferred embodiment shown in FIGS. 8A and 8B,even though the rear lid 20 is moved to the lifted position with theguide pins 39 positioned above and departing partially from the upperends of the guide grooves 40, the triangular protuberances 71 serve toguide the guide pins 39 smoothly into the associated guide grooves 40with the guide pins 39 sliding along the inclined face 71a as the rearlid 20 in the lifted position is moved towards the lowered position inresponse to the movement of the top lid 19 from the rear positiontowards the front position then following the movement of the front lid17 from the upwardly oriented position towards the forwardly orientedposition. Thus, it will readily be understood that the rear inclinedface 71 plays an important role to facilitate a smooth movement of therear lid 20 from the lifted position back towards the lowered position.

In addition, the use of the inclined upper ends 73 of the inner sidefaces 40b of the respective guide grooves 40, which flare the upper endsof the guide grooves in cooperation with the inclined faces 71a of thetriangular protuberances 71, is also effective not only to smoothlyguide the rear lid 20 rearwardly towards the lifted position at a finalstage of movement of the top lid 19 towards the rear position, but alsoto guide the guide pins 39 in cooperation with the inclined upper ends73 so as to be smoothly received into the associated guide grooves 40 asthe rear lid 20 is moved from the lifted position towards the loweredposition.

As described hereinbefore, when the top lid 19 is in the front position,the triangular protuberances 71 are received in the respective recesses72 defined in the top lid 19 to close the upper opening of the loadingbay 6. Therefore, no gap is substantially formed between the upper faces70 of the inner side walls 7 and the opposite ends of the top lid 19 tothereby avoid any possible ingress of foreign matter into the loadingbay 6.

In the case where the front, top and rear lids 17, 19 and 20 areoperatively linked together such as in the present invention, asufficient clearance is required at various joints and guide grooves tofacilitate a smooth movement of each of those lids. The stroke ofmovement of each of those lids must also be given a sufficient allowanceto provide a margin relative to the magnetic tape player or deck. Theseconsiderations are important particularly in the case of a compactmagnetic tape cartridge and, for example, if the front lid 17 is made topivot 90° to open, an angle of opening of 100° may often be required topermit the front lid 17 to open.

In the case of such a magnetic tape cartridge, accumulation of designerrors occurring in the front, top and rear lids 17, 19 and 20 mayresults in such a possibility that, when the front lid is pivoted thefull stroke of pivotal movement hereof, the guide pins 39 integral withthe front lid 17 may depart from the associated guide grooves 40. Oncethis happens, a problem would occur that the magnetic tape cartridgewill be entangled within the magnetic tape player.

In accordance with a third preferred embodiment of the presentinvention, means is provided in the top lid 19 for regulating themaximum angle of opening of the front lid 17. More specifically, asshown in FIGS. 9 and 10A to 10C, by adjusting the position at which adust removal wall 80, dimensions have been so chosen that, when theguide pin 29 integral with the top lid 19 is brought into engagementwith a front end of the dust removal wall 80, the angle of opening ofthe front lid 17 can be set to 90°. Even in this design, since the guidepin 29 integral with the top lid 19 can slightly slide over the dustremoval wall 80, there is no possibility that entanglement of themagnetic tape cartridge within the magnetic tape player resulting froman insufficient angle of opening of the front lid 17 will occur.Moreover, any possible departure of the guide pins 39 from theassociated guide grooves 40 which would otherwise occur if the front lid17 is excessively opened, i.e., moved towards the upwardly orientedposition, will not occur.

As best shown in FIG. 9, foreign matter deposited in the guide grooves33 defined in the side walls 24 is scraped by the guide pins 29 and thenexpelled rearwardly of the guide grooves 33 as the top lid 19 is pivotedto open, i.e., pivoted towards the rear position. However, in theillustrated example, since the dust removal wall 80 is formed so as tocontinue from the rear end of each guide groove 33, the foreign mattercollected by the associated guide pin 29 is pushed towards the dustremoval wall 80 and remains there when the top lid 19 is moved towardsthe front position. Accordingly, as the foreign matter is repeatedlypushed towards the rear end of the associated guide groove 33, theforeign matter accumulated at the rear end of the guide groove 33 issubsequently pushed outwardly of the casing having been guided along thedust removal wall 80, and therefore, there is no possibility that theaccumulated foreign matter may remain there in the form as gathered andcompressed.

FIGS. 10A to 10B illustrate respective modifications of the dust removalwall 80. In the example shown in FIG. 10A, each guide groove 33 has itsrear end rounded and the dust removal wall 80 is so shaped as torepresent a portion of the circle that extends from one straight portionof the guide groove 33 to the opposite straight portion of the guidegroove 33.

In the example shown in FIG. 10B, the dust removal wall 80 is sodesigned as to extend diagonally downwardly from the rear end of theguide groove 33 to provide an inclined passage.

In the example shown in FIG. 10C, the dust removal wall 80 is sodesigned as to extend downwardly from the rear end of the guide groove33 to provide an inclined passage. It is to be noted that the dustremoval wall 80 may have an arcuately protruding surface or an arcuatelyrecessed surface.

According to the present invention as hereinbefore described fully, eachof the cylindrical bosses 11 is comprised of the top and bottom bosssegments 12 and 13 integral with the respective top and bottom casinghalves 1a and 1b, said top boss segment 12 having an outer diametersmaller than that of the bottom boss segment 13 to allow that lateralportion 12a of the periphery of this top boss segment 12 to protrudeinto the loading bay 3 a radial distance smaller than that lateralportion 13a of the periphery of the bottom boss segment 13. Accordingly,it is possible to avoid any possible interference between the bosses 11and the rear lid 20 while a sufficient diameter is secured in each ofthe positioning holes 9 and, therefore, a smooth movement of the rearlid 20 between the lowered and lifted position is possible, therebymaking it possible to make the system compact.

Also, a transit between the top and bottom boss segments 12 and 13 ineach boss 11 is defined by the outwardly tapering surface 15 formed atthe upper end of the bottom boss segment 13. Accordingly, even thoughthe path of movement of the rear lid 20 between the lowered and liftedpositions is defined at a position slightly rearwardly with respect tothe ideal path of movement thereof, the rear lid 20 may slide over theoutwardly tapering surface 15 to facilitate a smooth movement of therear lid 20.

Although the present invention has been described in connection with thepreferred embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications areapparent to those skilled in the art. For example, although in theforegoing description, the cartridge has been described as accommodatingthe length of magnetic recording tape, the cartridge embodying thepresent invention may be used to accommodate a length of head cleaningtape for cleaning one or more magnetic recording and/or reproducingheads used in the tape player. Accordingly such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims, unless they departtherefrom.

What is claimed is:
 1. A magnetic tape cartridge which comprises:acasing including top and bottom panels and a peripheral wall disposedbetween the top and bottom panels to keep them spaced apart a distanceto define a tape chamber, said peripheral wall including front and rearwall sections and a pair of side wall sections, all assembled togetherto render the tape cartridge to represent a generally rectangularbox-like configuration and also including box arms protruding outwardlyfrom the front wall section in communication with the tape chamber so asto leave a loading bay that opens upwardly frontwardly and downwardlyand is thus delimited by upwardly, frontwardly and downwardly orientedopen areas; a pair of freely rotatable reels accommodated within thecasing; a length of magnetic recording tape having its opposite endanchored to said reels, respectively, and adapted to travel from onereel to the other reel, when the tape cartridge is in use within amagnetic recording and/or reproducing apparatus, with a portion of thelength of magnetic recording tape traversing across the loading bay at alocation spaced a distance from the front wall section; a lid assemblyfor selectively concealing and exposing that portion of magneticrecording tape and including front, top and rear lids operatively linkedtogether; said front lid being carried by the casing for pivotalmovement about a transverse axis, extending parallel to the front wallsection, between first and second positions, said front lid in saidfirst position opening the frontwardly oriented open area of the loadingbay, but said front lid in said second position closing position closingthe frontwardly oriented open area of the loading bay; said top lidhingedly connected with the front lid and movable between third andfourth positions in unison with the movement of the front lid betweenthe first and second positions, respectively, said top lid in said thirdposition closing the upwardly oriented open area of the loading bay, butsaid top lid in said fourth position opening the upwardly oriented openarea of the loading bay; said rear lid hingedly connected to the top lidand movable between fifth and sixth positions in unison with themovement of the top lid between the third and fourth positions,respectively, said rear lid in said fifth position being positionedwithin the loading bay and rearwardly of the front lid to substantiallyconfine that portion of magnetic recording tape within a space delimitedbetween the front lid in the second position and the rear lid in thefifth position, said rear lid in said sixth position being positionedgenerally above the loading bay and in part beneath the front lid in thesecond position and in part beneath the top lid in the fourth position,that portion of magnetic recording tape being exposed to the outsidewhen the front lid is moved to the first position accompanied bymovement of the top lid to the fourth position which is in turnaccompanied by movement of the rear lid to the sixth position; and atleast first and second, generally cylindrical bosses extending betweenthe top and bottom panels of the casing within the casing; each of saidfirst and second cylindrical bosses being positioned at a point ofintersection between an inner side wall of the respective box arm, whichconfronts the loading bay, and the front wall section so as to partiallyprotrude laterally into the loading bay; each of said first and secondcylindrical bosses having a positioning hole defined axially therein soas to extend exteriorly through one of the top and bottom walls of thecasing; and each of said first and second cylindrical bosses includingupper and lower boss segments aligned axially with each other, saidupper boss segment having an outer diameter smaller than that of thelower boss segment wherein a transit between the upper and lower bosssegments is defined by a tapering surface defined in an upper end of thelower boss segment, said tapering surface tapering radially inwardlytowards the upper boss segment.
 2. The magnetic tape cartridge asclaimed in claim 1, wherein said casing is comprised of upper and lowercasing halves having the top and bottom panels, respectively, andwherein said upper and lower boss segments are formed integrally withthe top and bottom panels, respectively, said upper and lower bosssegments; being utilized to pass respective set screws therethrough toconnect the upper and lower casing halves together.
 3. The magnetic tapecartridge as claimed in claim 1, wherein said top lid has a ribextending lengthwise of the top lid and said rear lid has a pair ofbearing protuberances protruding laterally outwardly from one ofopposite edges thereof adjacent the top lid and, said bearingprotuberances carrying corresponding pivot pins that are pivotallyinserted into respective opposite ends of said rib so as to define apivot axis through which the rear lid is hingedly connected with the toplid, said one of the opposite edges of the rear lid being formed with anelongated wall member extending between the bearing protuberances so asto encircle generally halfway the rib.
 4. The magnetic tape cartridge asclaimed in claim 3, wherein said elongated wall member protrudeslaterally from the rear wall in both directions confronting thedirection of thickness of the rear lid.
 5. A magnetic tape cartridge foraccommodating a length of reeled magnetic recording tape, whichcomprises:a casing including top and bottom panels and a peripheral walldisposed between the top and bottom panels spaced apart a distance todefine a tape chamber, said peripheral wall including front and rearwall sections and a pair of side wall sections, said wall sectionshaving respective first profiled guide grooves of a similar profiledefined therein; a box arm protruding outwardly from a respective end ofthe front wall section adjacent the associated side wall section,opposite portions of the side wall sections adjacent the box arms havingrespective inner surfaces that are formed respectively with secondprofiled guide grooves of a similar profile, said box arms being incommunication with the tape chamber so as to form a loading bay thatopens upwardly, frontwardly and downwardly and that is delimited byupwardly, frontwardly and downwardly oriented open areas; and a lidassembly for selectively concealing and exposing a portion of the lengthof magnetic recording tape traversing the loading bay, said lid assemblycomprising; a generally elongated front lid being carried by the casingfor pivotal movement about a transverse axis, extending parallel to thefront wall section, between a first position, in which said front lidcloses the frontwardly oriented open area of the loading bay, and asecond position in which said front lid opens the frontwardly orientedopen area of the loading bay; a generally elongated top lid having alongitudinal axis lying widthwise of the casing and also having top lidlongitudinal edge portions opposite to each other, one of saidlongitudinal edge portions being hingedly connected with the front lid,the other of the top lid longitudinal edge portions having top lid guidepins protruding outwardly respectively from opposite ends of the toplid, said top lid further having a pair of spaced apart top lid bearingspositioned generally intermediate between the opposite longitudinal edgeportions, said top lid mounted on the casing with the top lid guide pinsslidingly received within the first profiled grooves for movementbetween third and fourth position in unison with the movement of thefront lid between the first and the second positions, respectively, saidtop lid in said third position closing the upwardly oriented open areaof the loading bay, but said top lid in said fourth position opening theupwardly oriented open area of the loading bay; and a generallyelongated rear lid having a longitudinal axis lying widthwise of thecasing and also having rear lid longitudinal edge portions opposite toeach other, one of said rear rid longitudinal edge portions beinghingedly connected with the top lid throughout he top lid bearings, theother of the rear lid longitudinal edge portions having a pair of spacedapart legs protruding therefrom towards the front wall section, saidlegs having rear lid guide pins that are slidingly engaged in therespective second profiled guide grooves, said rear lid being movablewith the rear lid guide pins engaged in the second profiled guidegrooves between fifth and sixth position in unison with the movement ofthe top lid between the third and fourth positions, respectively, saidrear lid in said fifth position being positioned within the loading bayand rearwardly of the front lid to substantially confine a said portionof the magnetic recording tape within a space delimited between the toplid and in the first position and the rear lid in the fifth position,said rear lid in said sixth position being positioned generally abovethe loading bay and in part beneath the front lid in the second positionand in part beneath the top lid in the fourth position, said portion ofthe magnetic recording tape being exposed to the outside when the frontlid is moved to the second position, accompanied by movement of the toplied to the fourth position which is in turn accompanied by movement ofthe rear lid to the sixth position; and wherein each of said box armshas a top wall adjacent to and substantially parallel to the top panelof the casing, and each of the second profiled guide grooves isdelimited by opposite inner side faces and has an upper end openingoutwardly of the casing through the associated top wall of the box arm,one of the opposite inner side faces of each second profiled guidegroove terminating at a level higher than the level of a top surface ofthe top panel and also higher than the other of the opposite inner sidefaces thereof.
 6. The magnetic tape cartridge as claimed in claim 5,wherein said one of the opposite inner side faces of each secondprofiled guide groove also terminates at a level higher than the levelof a top surface of the top wall of the respective box arm.
 7. Themagnetic tape cartridge as claimed in claim 5, wherein a generallytriangular protuberance is provided on the top wall of each box arm tothe level higher than the level of the top surface of the top panel andalso higher than the other of the opposite inner side faces thereof. 8.The magnetic tape cartridge as claimed in claim 5, wherein side faces ofeach second profiled guide groove is chamfered to define an inclinedguide face continued to such other of the inner side face.